Ever wonder why steroids are prescribed during an MS flare? It's because glucocorticoids, like prednisone, close up a permeable blood brain barrier through their effect on endothelial cells. When the blood brain barrier closes up, immune cells and plasmic particles cannot get into brain tissue, and inflammation calms down. But glucosteroids cannot be used continually, as their effect on tight junctions lessens and resistance builds up. https://www.frontiersin.org/articles/10.3389/fimmu.2016.00592/full

Ever wonder why Vitamin D is so important for people with MS? Vitamin D is also a steroid hormone. It's not a vitamin at all. It also helps close a permeable blood brain barrier, through its protective action on endothelial tight junctions. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4376709/

Researchers have known about the effect of steroids on the blood brain barrier in MS for decades.. So why don't we hear about it? Why hasn't there been more MS research into why the blood brain barrier's endothelial cells are not working? Is it because examining endothelial cells means that MS is not autoimmune?

Actually, that's exactly why. The DMTs do not work if the blood brain barrier remains permeable. https://www.mdedge.com/clinicalneurologynews/article/163875/multiple-sclerosis/blood-brain-barrier-health-may-signal-early

Because it's not just immune cells gaining access to brain tissue. When the BBB is permeable, all kinds of plasmic particles cross over. Iron, viruses, bacteria, clotting proteins, and yes, t and b cells. And all of these plasmic particles cause inflammation, kill neurons and degrade myelin. Heal the blood brain barrier, heal the brain, stop MS progression.